Apparatus for and method of cooling liquids



`Patented Nov. 22, 1949 7 APPARATS FOR AND METHOD OF COOLING LIQUIDS l Gardiner M. Rogers and Charles Osborn Mackey, n Ithaca, N. Y., assignors to Orange-Crush Company, Chicago, Ill., a corporation of Illinois Application April 28,1945, serial No. 590,816

7 claims. (ci. ca -91.5)

This invention relates to a refrigerating method and apparatus whereby heat is\ transferred from a warm body, such as a water coil or tank, a cooling cabinet o r other receptacle, to a very cold primary refrigerant, such as solidifled CO2 (Dry Ice), through the medium of a secondary refrigerant, such as ethyl alcohol, the circulation -of which is automatically controlled in a simpleand eiiicient manner.

" An important object of the invention is the provision of a refrigerating systemv of this character in which the circulation of the secondary refrigerant is accomplished through thermo- Y syphonic action and requires no external power means or medium.

Another object is to provide in such a system a thermostatic control of the flow of the secondary refrigerant responsive to the temperature of the substance to be cooled so as to automatically maintain the latter within a predetermined temperature range. A further object of the invention is to provide in conjunction with the primary refrigerant a l essential but is desirable for reasons which will heat exchanger of such form and arrangement as to cause rapid and eflicient transfer of heat from' the secondary to the primary refrigerant, and to facilitate the thermo-syphonic circulation of said secondary refrigerant.

An important advantage of the invention is that the system provided thereby is well adapted not only for cooling substances which it is desired to keep at an approximately constant moderate temperature, such for example as beverages or the water component thereof -in a dispensing device, but-also for quick freezing of certain types of commodities, such, for example, as various food products, in the zone around the very cold primary refrigerant and the preservation of the frozen products in the zone which is maintained at a controlled moderate'temperature by the secondary refrigerant.

Other objects and advantages of the invention will become apparent from' the following description, taken in connection with the accompanyingdrawings, in which: y

Fig. 1 is a vertical sectional view of an apparatus illustrating the principles of our invention; and

y Fig. 2 is a horizontal sectional view taken substantially on the section line 2-2 of Fig. 1.

While in actual practice the apparatus of the invention might take various forms depending uponthe use for which any particular unit or installation might be designed, we have shown the elementsin a simple and somewhat diagramlater appear. Said heat exchanger is of such construction as to provide an extensive surface area and may be, for example, in the form of a honeycomb radiator such as those used in automobiles and other apparatus in which the use of a cooling medium is required. Certain of the cells of the radiator are illustrated at i 9 in Fig. 2, it being understood that the illustration is fragmentary and that the remainder of the body of the radiator is the same although not so shown. A block of solidified carbon dioxide (Dry Ice) 2| is shown as resting upon the top of the radiator. It will, of course, be understood that the application of heat to the Dry Ice will result in a change of phase from solid ,to gas and that there will therefore be no liquid drip from the radiator. In order to prevent such liquid -drip the boiling point of the primary refrigerant must be at a lower temperature than the freezing point (or the saturation pressure at the triple point must be higher than atmospheric pressure). Carbon dioxide with a boiling point of -l09 F. and a freezing point of F. meets this requirement.

Through sublimation the Dry Ice will enter the interstices of the radiator so that in time practically the entire exposed surfaces will -be covered, thus providing for very .rapid and eilicient heat exchange between the contents of the radiator and the Dry lIce on the exterior thereof.

In the compartment I4 there is a tank 22 which contains a liquid refrigerant 23, which is preferably ethyl alcohol but may be brine or other liquid having a freezing point below that of the primary". refrigerant, such as methyl alcohol, ethyl ether, hexane, methylene chloride, pentane, and trichloroethylene. The secondary refrigerant should have a freezing point below the temperature of sublimation of the primary refrigerant in order to prevent freezing of the secondary refrigerant with consequent stoppage of its circula- :Maasai tion. Additional desirable propertiesvof the'sec` ondary refrigerant are a high coefcient of cubical expansion, a high specific heat and a boiling point above the highest temperature ofuse. The foregoing substances meet these conditions.

Extending upwardly from said tank 22 and communicably connecting the same with the radiator I6 are two pipes 24 and 25, and these pipes, as well as the radiator, are also filled with said liquid.

A coil 26 for receiving water or other liquid to be cooled is positioned in the tank 22 and is connected with an inlet pipe 21 by means of a valve diagrammatically illustrated at 28. Said coil is connected from its other end with a tank 29 into which the cooled liquid is discharged, and an outlet pipe 3| leads from said tank 29.

The lower ends of the pipes 24 and 25 are bent to form short horizontal portions 32 and vertical portions 33, the latter passing through the top wall of the tank 22 with which they have a liquidtight seal as indicated at 34. The lower ends of said vertical portions are flared to provide seats 35 for valves 36 supported on stems 31 depending from a horizontal rod 38. This rod in turn is connected to a bellows 39 by means of a link 4I secured at one end to said rod at a central point and at the other end to the lower leaf of said bellows. A tube 42 extends from the top of the bellows .to a bulb 43 located in the tank 29, a suitable thermal fluid being contained in said bulb, tube and bellows to cause expansion and contraction of the bellows in response to changes of temperature in the vicinity of the bulb in accordance with the well known principle of operation of devices of this character.

The liquid refrigerant 23 becomes very cold in the heat exchanger I6 and in cooling becomes more dense and heavier, which causes it to ow down through'the pipe 25 into the tank 22. In the latter tank it abstracts heat from the coil 25 and tank 29 which contain the substance to be cooled and this causes it to become less dense and lighter so that it rises through the pipe 24 to the upper end of the heat exchanger I6 through which the heat is transferred to the primary refrigerant 2 I. In other Words, a thermosyphonic action is set up which results in the transfer of heat from the water or other substance to be cooled to the cold producing medium, such as the block of Dry Ice resting upon the exchanger I6.

As above noted, said exchanger I6 may be mounted in an inclined position, sloping downwardly from left to right (viewing Fig. 1), which greatly facilitates the flow of the liquid refrigerant induced by the thermosyphonic action above described, and permits a large area of contact between the Dry Ice and the heat exchanger. However the heat exchanger could be mounted in a vertical position with the inlet at the top and the outlet at the bottom. From certain aspects of the invention the specic manner in which the heat exchanger is mounted may be regarded as immaterial.

A standpipe 44 is provided at the upper end of the radiator I6 to care for any possible excess liquid in the latter. In this connection it may be noted that most liquids which might be used as a secondary refrigerant increase in density and in specific volume with a decrease in the temperature. The standpipe 44 acts as a reservoir (or contraction tank) to permit such decrease in volume without formation of a vapor space in the heat exchanger.` Complete contact of the liquid secondary refrigerant with the metal walls of the exchanger is highly desirable if not necessary for a. rapid rate of heat transfer from the secondary refrigerant to the primary refrigerant.

Such gas as is given of! by the Dry Ice 2I due to evaporation is retained in the upper compartment I3 by the partition I5 which has flanges Il' welded or otherwise tightly secured to the inner sheet of the cabinet wall. The openings in said partition I5 for the pipes 24 and 25 are sealed around said pipes by means of suitable packings or solder indicated at 45. 'I'his prevents carbon dioxide gas from getting into the chamber I4 where an accumulation of such gas might cause chilling of the latter below the desired point.

It will now be apparent that the temperature of the portion of the secondary refrigerant surrounding the coil 26 and tank 29 will be automatically controlled in accordance with the temperature of the contents of the tank 29 in which (in the particular construction shown) the bulb 43 is placed. When the temperature in said tank tends to become too low the thermal fluid in the bulb-and-bellows system will contract thereby causing the bellows to close the valves 36 which cuts off the flow of the liquid refrigerant from the cold exchanger I6. When the temperature in tank 29 rises to a predetermined point due to the absorption of heat by the liquid refrigerant from the contents of the coil 26 and said tank 29, the thermal liquid will expand, causing the valves 36 to be opened and reestablishing the circulation of the liquid refrigerant through said exchanger I6. Thus the substance to be cooled may be kept at desired temperature.

It will be evident that, since the coil 29 and tank 29 are completely submerged in the liquid secondary refrigerant 23, the surfaces of these elements will not be subject to frosting and the refrigeration process need never be halted for defrosting purposes.

It will be further evident that instead of cooling a liquid in a coil and/or tank as shown, the secondary refrigerant could be used to cool, and maintain at desired temperature, other types of products, including solids, arranged in heat exchange relation with said refrigerant. Also the primary refrigerant, in addition to its function of cooling the secondary refrigerant, might be used' for other purposes, as, for example, the f quick freezing of certain foods or other products in a suitable receptacle in heat exchange relation with the primary refrigerant, and the preservation of the frozen products at a controlled moderate temperature in a suitable receptacle in the compartment which is cooled by the secondary refrigerant.

The foregoing detailed description of a simplied adaptation of the method and apparatus of our invention is of course only illustrative and no unnecessary limitations should be implied therefrom but the appended claims should be construed as broadly as permissible in view of the prior art.

We claim:

1. A refrigerating system comprising a heat exchanger arranged in direct heat exchange relation with a very cold primary refrigerant, such as CO2,A said heat exchanger being mounted in a generally horizontal but somewhat inclined position, a container spaced and segregated from` liquid refrigerant having than that of said primary refrigerant, whereby heatv may be transferred from said liquid to be refrigerated to said primary refrigerant.

2. A refrigerating system comprising a heat exchanger of the honeycomb radiator type arranged in direct heat exchange relation with a very cold primary refrigerant, a container spaced and segregated from said heat exchanger, a submerged receptacle, within said container for receiving a liquid to be refrigerated, and means for circulating from said heat exchanger to said container and back to the heat exchanger by thermo-syphonic action a liquid refrigerant having a lower freezing point than that of said primary refrigerant, whereby heat may be transferred from said liquid to be refrigerated to said primary refrigerant.

3. A` refrigerating system comprising a heat exchanger arranged to be subjected to the cooling effect of a very cold primary refrigerant, acontainer spaced and segregated from said heat exchanger, a submerged receptacle Within said container for receiving a liquid to be refrigerated, means including a plurality of pipes communicably connecting said heat exchanger and container for circulating from said heat exchanger to said container and back to the heat exchanger by thermo-syphonic action a liquid refrigerant having a lower freezing point than that of said primary refrigerant, whereby heat may be transferredfrom said liquid to be refrigerated to said primary refrigerant, and a thermostatic control device including valves in said pipes for controlling the circulation of said liquid refrigerant by means of changes in the temperature of -said liquid to be refrigerated to thereby maintain the latter Within a desired temperature range.

4. A refrigerating system comprising a heat exchanger arranged to be subjected to the cooling effect of a very cold primary refrigerant, a con-l tainer spaced and segregated from said heat exchanger, a submerged receptacle within said container for receiving a liquid to be refrigerated, means including a plurality of pipes communicably connecting said heat exchanger and container for circulating from said heat exchanger to said container and back to the heat exchanger by thermo-syphonic .action a liquid refrigerant having a lower freezing point than that of said primary refrigerant, whereby heat may be transferred from said liquid to be refrigerated to said primary refrigerant, and a thermostatic control device including valves in said pipes, a bellows connected with said valves, a bulb in the zone of said liquid to be refrigerated and a tube connecting said bulb and bellows and containing a thermal fluid for controlling the circulation of said liquid refrigerant by means of changes in the temperature 0f said liquid to be refrigerated to thereby maintain the latter within a desired temperature range.

5. A refrigerating system comprising a heat exchanger arranged in direct heat exchange relation with a very cold primary refrigerant, such a. lower -freezing point as CO2, said heat exchanger being mounted at an angle to the horizontal, but somewhat inclined position, a'container spaced and segregated from said heat exchanger,- a submerged receptacle within said container for receiving a liquid to be refrigerated, and means for circulating from said heat exchanger to said container and back to the heat exchanger by thermo-syphonic action a. liquid refrigerant having a lower freezing point than that of said primary refrigerant, whereby heat may be transferred from said liquid to be refrigerated to said primary refrigerant.

6. The method of refrigerating which consists in circulating in a circuit a liquid refrigerant by thermo-syphonic action through a heat exchanger located in heat 4exchange relation with a very cold primary refrigerant having a freezing point above that of said liquid refrigerant, then into heat exchange relation with a body to be refrigerated spaced and segregated from said primary refrigerant and back to said first-mentioned heat exchanger to transfer heat from said body to said primary refrigerant, and controlling the flow of said liquid refrigerant thermostatically at'a plurality of points in said circuit by means of changes in the temperature of said body to thereby maintain the latter Within a desired temperature range.

7. A refrigerating system comprising a heat exchanger arranged to be subjected to the cooling effect of a very cold primary refrigerant, a container spaced and segregated from said heat exchanger, a receptacle within said container for receiving a substance to be refrigerated. means including a plurality of pipes communicably connectingsaid heat exchanger and container for circulating from said heat exchanger to said container and back to the heat exchanger by thermosyphonic action a liquid refrigerant having a lower freezing point thanthat of said primary refrigerant, whereby heat may be transferred from said substance to be refrigerated tosaid primary refrigerant, and a thrmostatic control device including valves in said pipes for controlling the circulation of said liquid refrigerant by means of changes in the temperature of said substance to be refrigerated to thereby maintain the latter within a desired temperature range.

GARDINER M. ROGERS.

CHARLES OSBORN MACKEY.

REFERENCES CITED The following references are of record in the file of this patent: 

